RF Stability Requirements in ILC: Instrumentation Issues

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RF Stability Requirements in ILC
Instrumentation Issues

• Marc Ross
• LLRF Meeting
• 17-Feb-2006

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Instrumentation

• Cavity BPMs
• S-band for linac
• X/C band for BDS
• L-band for SCRF HOM
• Buttons for DR
• Lasers
• Transverse deflecting (crab) structures
• Single pulse triggering

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Cavity Beam Position monitor

• 1000 ? large compared to existing installations
• Good LO phase
• Excellent clock

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Integration is the key

• Transverse structures may be in the middle of
  nowhere with minimal RF infrstructure
• Example
• TTF VUV FEL S-band deflection system
• 80 meters of open waveguide

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Instrumentation

• Example
• Deflecting cavity, like the TTF S-band LOLA
  structure
• Warm, 2856 MHz, single bunch from within a train,
  20MV peak, 100KeV/100 um, 10x nominal divergence
  at TTF, s_z/(?/2p) 1e-4 ?0.1deg, short pulse
  (1us)

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S-band deflectors
200 10 5000

• 0.001 for the BC, ? 1MeV ok
• 0.2 for undamped e ? 5 MeV
• .005 TTF ? 20 MeV

The size of this gives an indication of the
required phase stability
eV 1.6 L vP
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Mode-locked Laser wire

• High Q, feedback stabilized needs excellent RF
  source (100 MHz)
• Locked to 1300, resynchronizable
• (TTF 54 MHz)

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Valerie Ayvazyan, TTF
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